Sql commands for updating table

You can't use a JOIN statement in an UPDATE statement (JOINs are discussed later), so you need a way to query another table and base results on your update.You can use a SELECT statement in your WHERE clause.The second part of the statement is the column name you want to edit.In this example, the SQL statement updates the "first_name" column with new data.You could set table column values to NULL and alert the user.

You need a table in your statement, which must be spelled correctly.Just like the SELECT statement, string and date values should be encased in single quotes. If you misspell a column name, SQL throws you an error.The WHERE clause is formatted in the same way you formatted it in your SELECT statements, but we'll get into WHERE clauses later.If multiple records are returned in the WHERE clause, you update multiple records at once.The following SQL statement updates all records where the customer has a NULL value for the first_name column: UPDATE Customer SET first_name = ‘No Value' WHERE first_name IS NULL The following tables give you a before and after snapshot: Before Sometimes, you need to edit records based on a SELECT statement.

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The error can be catastrophic for your data if you don't have a backup.

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